class_docstr: Generate a new plot with overlapping ROC curves (roc1 + roc2)
  
  Parameters
  ----------
  a : ROC
      ROC plot
  
  b : ROC
      ROC plot
  
  Examples
  --------
  .. plot:: ../../examples/roc_add.py
  
  Notes
  -----
  .. versionadded:: 0.8.4
code: def __init__(self, a, b):
      self.a = a
      self.b = b
  
imports: import numpy
  import matplotlib.pyplot
  from sklearn.metrics import roc_curve, auc
  from sklearn.preprocessing import label_binarize
  from ..telemetry import SKLearnEvaluationLogger
  from ..util import is_column_vector, is_row_vector
  from sklearn_evaluation import __version__
  import json
  from pathlib import Path
  from sklearn_evaluation.plot.plot import AbstractPlot, AbstractComposedPlot
  from ploomber_core.exceptions import modify_exceptions
label_desc: Use image node_id 1 to create a new ROCAdd object from inherited base classes: AbstractComposedPlot with example: obj = ROCAdd(a, b)